Like fellow member Youngsaeng, he was born in the Chinese Year of the Tiger. He’s a Gemini and his blood type is B. He’s 180 cm or 5'11" tall.

He studied at Chungwoon University and got a degree in electronic digital music from Kyonggi Universty. Like Jungmin and Hyungjun, he's from Seoul.

He has an older brother. His family used to have a fashion business.

Hyungjoon dropped out of school to pursue his dream of becoming a singer. He was waiting tables in a family restaurant when he was approached by a management company. He was set to be a part of a group to debut in China, but the group disbanded. He then started training under SM Entertainment before moving to DSP Media. He originally trained as a rock singer but was asked to attend dance classes.

He debuted as the leader of SS501 in 2005. In addition to their musical activities, SS501 participated in two reality shows, “Thank You for Waking Us Up” (2005) and “Thank You for Raising Us” (2006), that profiled the group’s life together. They also appeared in MNet’s “Idol World” in 2007, which showed SS501 doing various missions in Japan.

He joined the cast of MBC variety reality show “We Got Married” on May 11, 2008, with Hwang Bo, who is 6 years his senior. They achieved high popularity acting as a newlywed couple. Due to his appearance on “We Got Married,” he was cast in “Boys over Flowers,” the Korean version of “Hana Yori Dango,” as Yoon Jihoo, one of the members of the famous F4.

Known as the “Lettuce Couple,” Hyunjoong and Hwang Bo went on to win MBC’s Best Couple Award on December 28, 2008. They made their official exit from “We Got Married” on December 14, 2008, due to scheduling conflicts presented by “Boys over Flowers.” The drama was a huge media and ratings sensation in Korea during its run from January to March 2009. Hyunjoong won the Popularity Award at the Seoul International Drama Awards 2009 and the Popularity Award for Television at the 45th PaekSang Arts Awards in February of 2009. He later took on the role of Baek Seungjo in “Playful Kiss.”

He’s signed to KeyEast Entertainment. He plays the guitar, bass, piano, and drums. He collects guitars, some of which he bought himself, some of which are gifts from fans.

Hyunjoong’s hobbies are swimming, exercising, basketball, and football. He says that he wasn’t good at holding chopsticks until he had to act in “Boys over Flowers.” He doesn’t like to speak English because he’s self-conscious about his pronunciation.